Many phenomenon occur that have the adverse effect of causing teeth to become badly discolored and in many cases, teeth of children or adults become discolored during the formative period or later. Some of the causes of tooth discoloration are pharmaceutical discoloration that occurs when children are required to take certain drugs. Certain drugs have been known to cause the teeth of children to have various shades of yellow or brown if such drugs are taken before the permanent teeth of a child erupt. Discoloration also occurs due to the diet of persons that live in certain parts of the world, largely due to the minerals that are ingested along with the water that is consumed. The dental patient may also have a hyperplastic condition where the enamel of the teeth does not fully develop, causing the teeth to become easily discolored. A hyperplastic condition may also be evident, where the teeth of the patient may have an excess of mineral salt deposit that causes the teeth of the patient to have white spots. (Metabolic diseases such as those releasing bile pigments or hemorrhagic disturbances that release blood pigments may cause a discoloration of teeth. Bacteria frequently cause staining of teeth, e.g., green stain or tobacco stain.)
Thus far, there has been no effective method of treating discolored teeth in order to give them a pleasing cosmetic appearance. In the past, the only effective way the cosmetic appearance of teeth could be improved is for the teeth to be capped with plastic or porcelain crowns. This is a very expensive and time consuming procedure and the costs involved have the effect of eliminating cosmetic capping for all but a few patients. Decorative inlays have also been employed in the past but the difficulty of bonding materials to the enamel of teeth effectively prevent this procedure from being commercially feasible in the practice of dentistry.
When teeth become fractured or cariously involved, it frequently becomes necessary to restore the teeth to their proper shape and appearance to promote proper incisive and masticatory function and for cosmetic purposes. If a tooth has become fractured and restoration is desirable, in the past restoration has been accomplished by application of crowns to the teeth, which crowns have been composed of metal materials such as gold and plastic materials, such as methyl methacrylate polymer. An acceptable restoration has been accomplished in the past by application of jacket crowns to the teeth and by application of porcelain that is fused to gold crowns. These crowns typically involve a great deal of expense and also involve a great deal of dental chair time for application. For example, restoration of teeth by application of gold crowns may cost in the order of $200 to $225 and may require as much as three hours chair time in order to complete the installation of each crown.
A primary disadvantage in the application of crown restorations to teeth is the requirement that the tooth be preshaped to the drastic degree in order that the crown may be properly applied thereto. For proper application of crowns it is necessary that the crown and the tooth be prepared in order to achieve resistance as retention of the crown. The crown, in a proper application, is retained in position on the tooth by proper fitting to provide resistance and retention and the presence of crown cement between the prepared tooth and the crown is primarily for the purpose of filling any voids that might exist and thereby prevent debris from becoming deposited in the voids between the crown and the prepared tooth. The cement disposed between the crown and the tooth, although providing a gripping function to some degree, does not provide the primary gripping function that retains the crown in physical assembly with a tooth structure. One reason for this is the fact that the cements that have been used in the past for cementing crowns to prepared teeth, during crown restoration of the teeth, is a water soluble material and in time, if a crack or fissure is present between the tooth and the crown, saliva will penetrate the joint between the crown and the tooth and dissolve the cement. If proper resistance and retention were not provided between the crown and the tooth, the crown would become separated quite readily from the tooth structure.
A more recently utilized method of tooth restoration has been utilized that is effective in restoration of fractured teeth as well as teeth that have developed caries. After etching of the teeth with an acid solution, such as 50 to 75 percent phosphoric acid or citric acid for a short period of time, for the purpose of removing mineral salts from the enamel surface and creating spaces or "micro pores" in the enamel where the mineral salts have been dissolved by the acid, a dental sealant material may be applied to the acid prepared enamel surface which sealant enters the micro pores and when polymerized, forms an intimate mechanical bond with the enamel surface of the tooth. The dental sealer material may be of the type that is produced by the reaction product of Bisphenol A and Glycidyl Methacrylate such as a product manufactured and sold under the trademark of Nuva-Seal by the Caulk Division of Dentsply International, Inc. of Millford, Delaware. The sealant product, referred to as "Nuva-Seal," is activated by Benzoin methyl ether catalyst prior to application thereof to a tooth surface and is polymerized after application to the surface by exposure to ultra-violet light.
After application of the sealant material to the prepared enamel surface of the tooth, a dental filler material may be applied to the prepared and sealed surface and may be shaped essentially to the original configuration of the tooth with a plastic shaping instrument. The dental filler material may also be of a character that is based upon the reaction product of Bisphenol A and Glycidyl Methacrylate which is also activated by Benzoin methyl ether catalyst and selectively polymerized by exposure to ultra-violet light. A dental filler material that is suitable for this purpose is sold by the Caulk Division of Dentsply International, Inc. under the trademark "Nuva-Fil." This material will not become polymerized until it is selectively exposed to ultra-violet light. The material, therefore, may be worked for whatever period of time is necessary to properly shape the tooth restoration to its desired physical characteristics and polymerization will occur in a few seconds time after application of ultra-violet light to the shaped material. After the dental filler material has been shaped and polymerized, the outer surface of the filler material and a portion of the exposed enamel at the marginal portions of the filler material may be finally shaped with appropriate sanding or grinding instruments and a coating of dental sealer material may be then applied to desirable portions of the restored tooth and may be subsequently polymerized by application of ultra-violet light.
Although excellent tooth restorations may be accomplished by the above noted use of ultra-violet light polymerized dental sealer and filler material, it is very difficult to achieve precise color matching of the restored tooth to the color of a adjacent teeth. The restoration process therefore is often less than desirable from aesthetic standpoint. The dental filler and sealer material is commercially produced in a few different shades in order that color matching may be accomplished as nearly as possible, but it is well known that wide variation in color and tooth appearance is found in the teeth of dental patients. It is virtually impossible to select from the few shades of materials that are available a material that is capable of precisely matching with the color and appearance of adjacent tooth if color matching is indeed desirable.
In many cases, it is not desirable to match the tooth restoration material with the adjacent teeth, especially when the patients natural teeth have become discolored to the point that the cosmetic appearance is undesirable.
In the event one or more teeth should be missing, it is typically necessary to employ a dental bridge wherein a dental prothesis is connected to teeth adjacent the opening produced by the missing tooth and an artificial tooth or pontic forming a part of the prothesis is supported in the space to prevent migration of the adjacent teeth. In view of the fact that bridge work may not be supported by the enamel of abutment teeth adjacent an opening, it is typically necessary to provide the adjacent teeth with crown restorations even though these teeth may be perfectly normal. The crowns may be provided with appropriate means for physical attachment of the bridge work in order to support the bridge work prothesis. It is, of course, undesirable to provide crown restorations for perfectly normal teeth, although in some cases this is necessary to avoid the problems that may occur by migration of teeth by absence of one or more of the patient's permanent teeth. It is desirable, therefore, to provide means for preparing the abutment teeth adjacent an opening caused by a missing tooth or teeth with means for positively securing a prothesis bridge work in place without necessitating the tooth preparation that is necessitated by application of bridge work support crowns.
It is therefore a primary object of the present invention to provide a novel method of providing teeth of a patient with a laminar overlay for the purpose of providing a pleasing cosmetic appearance to the teeth.
It is an even further object of the present invention to provide a novel preformed fully polymerized laminant that may be effectively bonded to the enamel surface of a patient's teeth for the purpose of improving the cosmetic appearance of the teeth and for the purpose of providing efficient low cost, cosmetically pleasing tooth restorations.
It is also an object of the present invention to provide a method of tooth restoration for cosmetic or functional purposes that may be simply and efficiently accomplished with little or no alteration of the physical characteristics of the tooth being treated.
It is another object of the present invention to provide a novel method of cosmetically or functionally restoring teeth wherein the entire restoration process may be accomplished in a short period of time without necessitating use of anesthesia.
It is an even further object of the present invention to provide a novel method of restoring fractured or cariously involved teeth that may be accomplished effectively through the use of low cost materials to provide a restoration having the exceptional quality and a pleasing cosmetic appearance.
Among the several objects of the present invention is noted the contemplation of a novel method of restoring fractured or cariously involved teeth wherein facings composed of a suitable plastic material may be bonded to the enamel of a tooth to be restored, which plastic material may, if desirable, have the external appearance of the patient's natural teeth and which material will also match the functional characteristics of the patient's teeth.
It is another important object of the present invention to provide a novel method of restoring teeth wherein preformed plastic facings may be employed, which facings may be marked with checks, stains, etc. to match the coloring and characteristics of the patient's adjacent teeth.
It is also an object of the present invention to provide a novel method of restoring teeth wherein a plastic facing may be applied to a tooth to be restored and may be inspected for physical shape and cosmetic appearance prior to permanent bonding of the plastic facing to the tooth's structure and if not satisfactory, the facing may be simply and efficiently removed and another substituted therefor in order to provide a pleasing cosmetic appearance. After the dentist, and perhaps also the patient, has approved the cosmetic appearance and physical shape of the restored tooth, the unpolymerized portion of the restoration may be selectively polymerized to complete the restoration process.
It is also an important object of the present invention to provide a novel method of restoring teeth wherein plastic material utilized in the restoration process may be selectively polymerized in place to provide a hard and durable restoration that, with responable dental care, will last for very long periods of time.
It is another feature of the present invention to provide anchor means for dental bridge work prothesis without necessitating grinding away of abutment teeth adjacent to an opening caused by a missing tooth or teeth that otherwise must be necessary in order to provide prothesis anchor crowns on the abutment teeth supporting the bridge work.
It is an even further feature of the present invention a method of restoring or otherwise treating a patient's teeth in order to provide for periodontal splinting of a patient's teeth.
It is also an object of the present invention to provide a method of restoring teeth, which restoration process if unsatisfactory when completed or, if such restoration becomes undesirable subsequent to a completion of the process, may be completely and efficiently removed from the tooth or teeth so involved, thereby returning the teeth to the original pretreatment condition thereof.
Other and further objects, advantages and features of the present invention will become apparent to one skilled in the art upon consideration hereof. The form of the invention, which will now be described in detail, illustrates the general principles of the invention, but it is to be understood that this detailed description is not to be taken as limiting the scope of the present invention.